1. Field
Embodiments of the inventive concept relate to a phase-shift keying (PSK) demodulator suitable for use in a radio frequency identification (RFID) system, and a smart card including the same.
2. Description of Related Art
Phase-shift keying is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal. Accordingly, a PSK signal encodes data by varying the phase of the reference signal by predetermined discrete phase shifts. A PSK demodulator determines the phase of the received signal and maps it back to the symbol it represents, thus recovering the original data.
Contactless RFID systems are being used in various applications. In particular, RFID systems including a smart card that can be recognized at a distance of several centimeters are being employed in mobile communication systems. A smart card typically includes a PSK demodulator that demodulates a PSK signal transmitted from a card reader. PSK demodulation allows the smart card to detect information carried in the PSK signal.
Conventional PSK demodulators use multi-phase clocks to convert phase information into time information. For this reason, a conventional PSK demodulator uses a clock generator circuit for generating a reference signal. However, the use of a clock generator circuit may undesirably increase the complexity and/or power consumption of a PSK demodulator.